JP4993132B2 - Foundation reinforcement method for existing structures - Google Patents

Description

  The present invention relates to a foundation reinforcing method for an existing structure that is suitable for reinforcing a foundation that is necessary when the weight of the structure increases due to the modification of an existing structure.

  If the existing structure increases the weight of the structure and the existing pile foundation has insufficient vertical bearing capacity relative to the weight of the structure after the repair, the foundation needs to be reinforced. Conventionally adopted as a reinforcement method for such a foundation is to build an overhanging part that is placed on the outer periphery of the bottom of the existing structure and placed on the top of the pile. In this method, the foundation is expanded (see, for example, Patent Document 1).

In this construction method, the load of the structure is increased and transmitted to the pile through the overhang portion, so that the weight increase of the structure is increased and supported by the pile. However, it is difficult to accurately transmit the load to the additional pile through the newly constructed overhanging portion, and an excessive load may be applied to the existing foundation pile, resulting in lack of reliability. In addition, the use of the existing structure is limited because a pile driving machine is carried around the existing structure and the pile is driven.
JP-A-2005-240297

  In view of the above, the present invention provides a foundation reinforcing method for an existing structure that can reinforce the foundation so as to reliably withstand the increase in the weight of the structure without restricting the use of the existing structure. That is the issue.

  In order to solve the above-mentioned problems, the present invention is a method for reinforcing the foundation of an existing structure, and a predetermined one or more foundation piles from a plurality of existing foundation piles that are the foundation of the existing structure And the step of excavating a horizontal hole that reaches the target pile along the bottom of the existing structure on the ground directly below the existing structure, exposing the upper part of the target pile to the side hole, and Excavate the ground around the target pile downward from the side hole, excavate a larger diameter hole than the target pile, and apply concrete to the enlarged hole and the upper part of the target pile exposed in the side hole. And a step of constructing a diameter-enlarged reinforcement part by concrete around the pile to be reinforced. Repeat the placement of the plate-shaped support material on the peripheral surface, the peripheral surface of the expansion hole Down multistage with placing pre-supports, when the arrangement of the pre-supports of the predetermined plurality of stages, characterized in that interposed a plurality of beam members radially between the reinforcement object pile with the pre-supports.

  According to the present invention, it is possible to reinforce the pile to be reinforced with the diameter-enlarged reinforcing portion and increase its vertical support force. And since the pile to be reinforced is selected from the existing foundation piles, the transmission failure of the load of the structure to the pile to be reinforced does not occur, and the increase in the weight of the structure is reliably supported by the pile to be reinforced. Therefore, the foundation can be reliably reinforced so as to withstand the increase in the weight of the structure. In addition, since most of the work for reinforcing the foundation is performed under the bottom surface of the existing structure, the existing structure can be used without any trouble during the foundation reinforcing work.

  Here, at the time of excavation of the enlarged hole, the pile to be reinforced loses support from the surroundings by the ground. However, in the present invention, the beam to be reinforced is supported from the periphery by the beam member interposed between the supporting material and the pile to be reinforced arranged on the peripheral surface of the enlarged diameter hole. Does not occur.

  Furthermore, according to this invention, a support layer can be visually confirmed by digging an enlarged diameter hole to the support layer in which the lower end of the reinforcement | strengthening pile is driven. Therefore, when the support layer is uneven and the pile to be reinforced is not sufficiently supported by the support layer, appropriate measures can be taken to increase the support force, and the certainty of foundation reinforcement is ensured. .

  Moreover, in this invention, after constructing | assembling a diameter expansion reinforcement part, it is desirable to provide the process of placing concrete in a horizontal hole and constructing an underground beam. According to this, the proof strength with respect to a horizontal load is strengthened, and earthquake resistance improves.

  Referring to FIGS. 1A and 1B, reference numeral 1 denotes a foundation pile such as a steel pipe pile driven into the ground F1, and 2 denotes an existing structure built on the foundation pile 1 as a foundation. A plurality of foundation piles 1 are provided at an equal pitch, and the lower ends thereof are driven into a support layer F2 such as a bedrock. Hereinafter, the foundation reinforcement construction method performed when the weight of the structure 2 increases by renovation of this existing structure 2 is demonstrated.

  In this foundation reinforcement method, one or more foundation piles 1 are selected as reinforcement target piles 1H in consideration of weight distribution from a plurality of existing foundation piles 1, and the reinforcement target piles 1H are expanded and reinforced. In the present embodiment, nine foundation piles 1 to # 9 in FIG. 1B are selected as reinforcement target piles 1H.

  When reinforcing the foundation, first, a vertical hole 3 deeper than the bottom surface 2a of the existing structure 2 is excavated adjacent to one side of the existing range of the foundation pile 1. Next, the ground F1 in the existing range of the foundation pile 1 immediately below the existing structure 2 is hardened by injecting a chemical solution from the standing hole 3 over a predetermined depth from the bottom surface 2a of the existing structure 2.

Next, as shown in FIG. 2 (a), the ground F1 hardened by injection of the chemical solution directly under the existing structure 2 is moved from the vertical hole 3 to the # 1 reinforcement target pile 1H along the bottom surface 2a of the existing structure 2. it reaches the first drilled lateral hole 4 _1, to expose the upper portion of the reinforcement object pile 1H of # 1 to lateral hole 4 _1. Incidentally, the lateral holes 4 _1, as the actual sequence of the foundation pile 1 can be confirmed visually, is drilled so as to pass through a plurality of sides of the foundation pile 1 comprising a reinforcing target pile 1H of # 2 and # 3. Further, installed on the wall surface of the lateral hole 4 ₁ As unbalanced load due to soil pressure in foundation pile 1 adjacent to lateral hole 4 ₁ does not act shoring (not shown).

Next, as shown in FIG. 2 (b), advancing digging soil F1 around the reinforcing target pile 1H of # 1 from lateral hole 4 ₁ downward, the support layer diameter expansion hole 5 of larger diameter than the reinforcement object pile 1H Drill to reach F2.

  In the excavation process of the diameter-expanded hole 5, the plate-shaped support material 6 is repeatedly arranged on the peripheral surface of the portion of the diameter-expanded hole 5 that has already been excavated every time a predetermined depth is excavated. Thereby, the supporting material 6 is arrange | positioned in the up-and-down multistage on the surrounding surface of the diameter expansion hole 5. FIG. Then, when arranging the supporting members 6 of a plurality of predetermined stages, for example, when arranging the supporting members 6 of the odd stages counted from the top, a plurality of beams radially between the supporting material 6 and the reinforcing target pile 1H. A member 7 is interposed.

  Here, at the time of excavation of the diameter expansion hole 5, the pile 1H to be reinforced loses support from the surroundings by the ground F1, and is likely to buckle. However, in this embodiment, since the reinforcement target pile 1H is supported from the periphery by the beam member 7 interposed between the support material 6 and the reinforcement target pile 1H, buckling of the reinforcement target pile 1H is prevented.

  In addition, in this embodiment, although the beam member 7 is interposed every other step between the support material 6 and the reinforcement object pile 1H, when the load which acts on the reinforcement object pile 1H is small, it is 2 It is also possible to interpose the beam member 7 with an interval of a step or more, and when the acting load on the reinforcement target pile 1H is large, the support material 6 of all the steps and the reinforcement target pile 1H A beam member 7 may be interposed between the two. The beam member 7 is generally made of steel, but a telescopic mechanical jack can also be used as the beam member 7.

  When excavation of the enlarged diameter hole 5 is completed, the support layer F2 is visually confirmed. And when the support layer F2 is non-uniform | heterogenous and the to-be-reinforced pile 1H is not fully supported by the support layer F2, an appropriate measure is taken so that support force may be raised. Moreover, the state of the pile 1H to be reinforced is visually confirmed, and when the deterioration is progressing, the repair is performed.

Next, as shown in FIG. 2 (c), the enlarged diameter bore 5 by Da設concrete to the upper periphery of the reinforcing target piles 1H exposed to (see FIG. 2 (b)) and lateral hole 4 in _1, be reinforced A diameter-enlarged reinforcing portion 8 made of concrete is constructed around the pile 1H. Note that a jack is inserted between the uppermost end portion of the enlarged diameter reinforcing portion 8 and the bottom surface of the existing structure 2 to apply prestress to the enlarged diameter reinforcing portion 8, and in this state, between the bottom surface of the existing structure 2. It is formed by placing concrete in the wall. Thereby, the load of the existing structure 2 is reliably transmitted to the diameter expansion reinforcement part 8. FIG.

When the build of the enlarged diameter reinforcing portion 8 is completed, concrete is over the front portion of the reinforcement object pile 1H of # 2 from the portion of the reinforcing target pile 1H of # 1 to lateral hole 4 _1. Then, proceed digging lateral hole _{4 1} to be reinforced piles 1H side of the # 2, drilling Edaana 4a reinforcing target piles 1H of # 2 (see FIG. 2 (a)), # this Edaana the 4a The upper part of 2 reinforcement object pile 1H is exposed. Then, excavation of a diameter expansion hole and construction of the diameter expansion reinforcement portion 8 are performed for the # 2 reinforcement target pile 1H in the same procedure as described above. Next, the concrete over the front portion of the reinforcement object pile 1H side holes 4 ₁ to # from the portion of the reinforcement object pile 1H of # 2 3 After Da設, lateral hole 4 ₁ to be reinforced piles 1H side of the # 3 It digs up and excavates the branch hole 4b for the # 3 reinforcement target pile 1H (see FIG. 2A), and exposes the upper part of the # 3 reinforcement target pile 1H in the branch hole 4b. Then, in the same procedure as described above, excavation of a diameter expansion hole and construction of the diameter expansion reinforcement portion 8 are performed for the # 3 reinforcement target pile 1H. Thereafter, concrete is cast over the portion of the reinforcement object pile 1H # 3 in lateral hole 4 ₁ to the inlet portion of the Tatsuana 3 side. Thereby, it is the underground which connects the enlarged diameter reinforcement part 8 of # 1 reinforcement object pile 1H, the enlarged diameter reinforcement part 8 of reinforcement object pile 1H of # 2, and the enlarged diameter reinforcement part 8 of reinforcement object pile 1H of # 3. A beam 9 ₁ (see FIG. 2D) is constructed.

Next, the ground F1 directly below the existing structure 2 passes along the bottom surface 2a of the existing structure 2 from the upright hole 3 to the side of the # 6 reinforcement target pile 1H and the side of the # 5 reinforcement target pile 1H. The second lateral hole 4 ₂ (see FIG. 2A) reaching the # 4 reinforced pile 1H is excavated. The reinforcement subject be reinforced piling and excavation and construction of the enlarged diameter reinforcing portion 8 of the enlarged diameter bore for 1H, transverse hole 4 ₂ # 4 reinforcing target pile 1H moiety from # 5 and # 4 in the same procedure as above Concrete placement up to the front part of the pile 1H, excavation of the branch hole 4c exposing the upper portion of the # 5 reinforcement target pile 1H, and excavation of the expansion hole for the # 5 reinforcement target pile 1H and an expansion reinforcement part 8 and the construction of the branch to expose the pouring of the concrete from the portion of the reinforcing target pile 1H lateral holes 4 ₂ # 5 to just before the portion of the reinforcement object pile 1H of # 6, the upper portion of the reinforcement object pile 1H of # 6 and drilling holes 4d, the construction of the reinforcing drilling diameter holes for the target pile 1H and enlarged reinforcing portion 8 of # 6, the concrete from the portion of the reinforcing target pile 1H lateral holes 4 ₂ # 6 to the inlet portion hitting Set up in order. Thereby, it is the underground which connects the diameter expansion reinforcement part 8 of the reinforcement object pile 1H of # 4, the diameter expansion reinforcement part 8 of the reinforcement object pile 1H of # 5, and the diameter expansion reinforcement part 8 of the reinforcement object pile 1H of # 6. The beam 10 ₂ (see FIG. 2 (d)) is constructed.

Next, the ground F1 directly below the existing structure 2 passes along the bottom surface 2a of the existing structure 2 from the vertical hole 3 to the side of the # 9 reinforcement target pile 1H and the side of the # 8 reinforcement target pile 1H. A third lateral hole 4 ₃ (see FIG. 2A) reaching the # 7 reinforced pile 1H is excavated. The reinforcement subject be reinforced piling and excavation and construction of the enlarged diameter reinforcing portion 8 of the enlarged diameter bore for 1H, # from the portion of the reinforcement object pile 1H of # 7 transverse bore 4 ₃ 8 # 7 in the same procedure as described above Concrete placement up to the front portion of the pile 1H, excavation of the branch hole 4e exposing the upper part of the # 8 reinforcement target pile 1H, and excavation of the expansion hole for the # 8 reinforcement target pile 1H and an expansion reinforcement portion 8 and the construction of the branch to expose the pouring of the concrete from the portion of the reinforcing target pile 1H lateral holes 4 ₃ # 8 to the front portion of the reinforcement object pile 1H of # 9, the upper portion of the reinforcement object pile 1H of # 9 and drilling holes 4f, the construction of the reinforcing target drilling diameter holes for piles 1H and enlarged reinforcing portion 8 of # 9, the concrete from the portion of the reinforcing target pile 1H lateral holes 4 ₃ # 9 to the inlet part hitting Set up in order. Thereby, the underground expansion connecting part 8 of the reinforcement target pile 1H of # 7, the expansion expansion part 8 of the reinforcement target pile 1H of # 8, and the expansion expansion part 8 of the reinforcement target pile 1H of # 9 are underground. A beam 9 ₃ (see FIG. 2D) is constructed. Finally, the vertical hole 3 is backfilled to complete the foundation reinforcement work.

According to the above-described foundation reinforcing method, the pile 1H to be reinforced can be reinforced with the diameter-enlarging reinforcing portion 8, and the vertical supporting force can be increased. And since the pile 1H to be reinforced is selected from the existing foundation pile 1, the transmission failure of the load of the structure 2 to the pile 1H to be reinforced does not occur, and the weight increase of the structure 2 is surely secured by the pile 1H to be reinforced. Supported by Therefore, the foundation can be reliably reinforced so as to withstand the weight increase of the structure 2. Further, since the plurality of reinforcement target piles 1H are connected by the middle beams 9 ₁ , 9 ₂ , and 9 ₃ , the horizontal load is applied to the reinforcement target piles 1 H via the underground beams 9 ₁ , 9 ₂ , and 9 _3. Can be borne well. As a result, the proof strength against horizontal load is enhanced and the earthquake resistance is improved. In addition, since most work for reinforcing the foundation is performed under the bottom surface of the existing structure 2, the existing structure 2 can be used without any trouble during the foundation reinforcement work.

(A) The longitudinal cross-sectional view of the foundation part of an existing structure, (b) The cutting | disconnection top view of the foundation part of an existing structure. Explanatory drawing which shows the process of the foundation reinforcement construction method of embodiment of this invention.

Explanation of symbols

F1 ... ground, 1 ... foundation pile, 1H ... reinforcement target pile, 2 ... existing structure, 2a ... bottom surface of existing structure, 4 ₁ , 4 ₂ , 4 ₃ ... horizontal hole, 5 ... expansion hole, 6 ... support material , 7 ... Beam member, 8 ... Diameter expansion reinforcement part, 9 ₁ , 9 ₂ , 9 ₃ ... Underground beam.

Claims (2)

A method of reinforcing the foundation of existing structures,
Select one or more predetermined foundation piles as the reinforcement target piles from multiple existing foundation piles that are the foundation of the existing structure, and reinforce along the bottom of the existing structure on the ground directly under the existing structure Drilling a horizontal hole reaching the target pile and exposing the upper part of the reinforcing target pile in the horizontal hole;
Digging the ground around the pile to be reinforced downward from the side hole, and excavating a larger diameter hole than the pile to be reinforced,
Providing concrete around the enlarged hole and the upper periphery of the pile to be reinforced exposed in the side hole, and constructing an enlarged reinforced portion with concrete around the pile to be reinforced,
In the process of drilling the expanded hole, the plate-shaped support material is repeatedly arranged on the peripheral surface of the expanded hole portion every time a predetermined depth is drilled. And a plurality of beam members are provided between the support material and the pile to be reinforced in a radial manner when the support materials are arranged in a predetermined plurality of steps. Foundation reinforcement method.   2. The foundation reinforcing method for an existing structure according to claim 1, further comprising a step of constructing an underground beam by constructing concrete in the lateral hole after constructing the diameter-enlarged reinforcing portion.

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